Consumptive and non-consumptive effects of predators vary with the ontogeny of their prey

Albert Pessarrodona, Jordi Boada, Jordi F. Pagès, Rohan Arthur, Teresa Alcoverro

Research output: Contribution to journalArticle

Abstract

Predators exert a strong influence on ecological communities by reducing the abundance of prey (consumptive effects) and shaping their foraging behavior (non-consumptive effects). Although the prevalence of trophic cascades triggered by non-consumptive effects is increasingly recognized in a wide range of ecosystems, how its relative strength changes as prey individuals grow in size along various life stages remains poorly resolved. We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. We conducted a series of field and laboratory experiments to determine how susceptibility to predation, prey behavioral responses, and grazing impact on algal cover vary with sea urchin size. The consumptive effects of predators were greater on smaller sea urchin size classes, which were more susceptible to predation. Unexpectedly however, predator non-consumptive effects acted only on larger sea urchins, significantly reducing their grazing activity in the presence of predator cues. Crucially, only these larger sea urchins were capable of overgrazing macroalgae in the field, with non-consumptive effects reducing sea urchin foraging activity and macroalgal grazing impact by 60%. The decoupling between risk and fear as prey grow indicates that the strength of consumptive and non-consumptive trophic cascades may act differently at different ontogenetic stages of prey. While the consumptive effects of predators directly influence population numbers, the consequences of non-consumptive effects may far outlive consumptive effects as prey grow, finding refuge in size, but not from fear.

Original languageEnglish
Article numbere02649
JournalEcology
Volume100
Issue number5
DOIs
Publication statusPublished - 1 May 2019

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ontogeny
Echinoidea
predator
predators
grazing
fearfulness
algae
trophic cascade
foraging
predation
overgrazing
macroalgae
effect
rocks
coralline alga
behavioral response
foraging behavior
ecosystems
refuge
sea

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Pessarrodona, Albert ; Boada, Jordi ; Pagès, Jordi F. ; Arthur, Rohan ; Alcoverro, Teresa. / Consumptive and non-consumptive effects of predators vary with the ontogeny of their prey. In: Ecology. 2019 ; Vol. 100, No. 5.
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Consumptive and non-consumptive effects of predators vary with the ontogeny of their prey. / Pessarrodona, Albert; Boada, Jordi; Pagès, Jordi F.; Arthur, Rohan; Alcoverro, Teresa.

In: Ecology, Vol. 100, No. 5, e02649, 01.05.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Consumptive and non-consumptive effects of predators vary with the ontogeny of their prey

AU - Pessarrodona, Albert

AU - Boada, Jordi

AU - Pagès, Jordi F.

AU - Arthur, Rohan

AU - Alcoverro, Teresa

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Predators exert a strong influence on ecological communities by reducing the abundance of prey (consumptive effects) and shaping their foraging behavior (non-consumptive effects). Although the prevalence of trophic cascades triggered by non-consumptive effects is increasingly recognized in a wide range of ecosystems, how its relative strength changes as prey individuals grow in size along various life stages remains poorly resolved. We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. We conducted a series of field and laboratory experiments to determine how susceptibility to predation, prey behavioral responses, and grazing impact on algal cover vary with sea urchin size. The consumptive effects of predators were greater on smaller sea urchin size classes, which were more susceptible to predation. Unexpectedly however, predator non-consumptive effects acted only on larger sea urchins, significantly reducing their grazing activity in the presence of predator cues. Crucially, only these larger sea urchins were capable of overgrazing macroalgae in the field, with non-consumptive effects reducing sea urchin foraging activity and macroalgal grazing impact by 60%. The decoupling between risk and fear as prey grow indicates that the strength of consumptive and non-consumptive trophic cascades may act differently at different ontogenetic stages of prey. While the consumptive effects of predators directly influence population numbers, the consequences of non-consumptive effects may far outlive consumptive effects as prey grow, finding refuge in size, but not from fear.

AB - Predators exert a strong influence on ecological communities by reducing the abundance of prey (consumptive effects) and shaping their foraging behavior (non-consumptive effects). Although the prevalence of trophic cascades triggered by non-consumptive effects is increasingly recognized in a wide range of ecosystems, how its relative strength changes as prey individuals grow in size along various life stages remains poorly resolved. We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. We conducted a series of field and laboratory experiments to determine how susceptibility to predation, prey behavioral responses, and grazing impact on algal cover vary with sea urchin size. The consumptive effects of predators were greater on smaller sea urchin size classes, which were more susceptible to predation. Unexpectedly however, predator non-consumptive effects acted only on larger sea urchins, significantly reducing their grazing activity in the presence of predator cues. Crucially, only these larger sea urchins were capable of overgrazing macroalgae in the field, with non-consumptive effects reducing sea urchin foraging activity and macroalgal grazing impact by 60%. The decoupling between risk and fear as prey grow indicates that the strength of consumptive and non-consumptive trophic cascades may act differently at different ontogenetic stages of prey. While the consumptive effects of predators directly influence population numbers, the consequences of non-consumptive effects may far outlive consumptive effects as prey grow, finding refuge in size, but not from fear.

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KW - Mediterranean Sea

KW - Paracentrotus lividus

KW - regime shift

KW - temperate reefs

KW - top-down control

KW - trait-mediated indirect interaction

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U2 - 10.1002/ecy.2649

DO - 10.1002/ecy.2649

M3 - Article

VL - 100

JO - Ecology

JF - Ecology

SN - 0012-9658

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